Implantable Patch Antenna Research Articles

Inductive and capacitive loaded miniaturized implantable patch antenna with circular polarization for bio‐medical applications

Inductive and capacitive loaded miniaturized implantable patch antenna with circular polarization for bio‐medical applications

Design of ultra-compact ISM band implantable patch antenna for bio-medical applications

AbstractIn this paper, an ultra-compact implantable antenna for biomedical applications is proposed. The proposed implanted meandered compact patch antenna is implanted inside the body at a depth of 2 mm. The proposed antenna was designed with Roger RO3003 (ɛr= 3) as substrate with an overall size of dimensions 5 × 5 × 0.26 mm3. The radiating element is a square patch antenna with different size rectangular slots and coaxial feeding. The proposed implantable antenna resonates at 2.45 GHz (from 2.26 to 2.72 GHz) frequency with a bandwidth of 460 MHz and a gain of −22.6 dB. The specific absorption rate has been considered for health care considerations, and the result is within the limits of the federal communication commission. The measured and simulated scattering parameters are compared, and good agreements are achieved. The proposed antenna is simulated and investigated for biomedical applications suitability.

A Wideband Circularly Polarized Implantable Patch Antenna for ISM Band Biomedical Applications

This communication presents a novel compact broadband circularly polarized (CP) implantable patch antenna for biomedical applications in 2.4 GHz industrial, scientific, and medical (ISM) band. By employing slots on the patch plane and shorting method, the whole size (including the superstrate) of the designed antenna can be enormously reduced to $9.8\times 9.8\times1.27$ mm3, which is equivalent to $0.0784\lambda _{0}\times 0.0784\lambda _ {0}\times 0.0102\lambda _ {0}$ ( $\lambda _ {0}$ is the free-space wavelength at 2.4 GHz). Under the premise of keeping a slotless ground, not only a good size reduction is realized but also the impedance bandwidth and the axial ratio (AR) bandwidth are greatly improved. A simulated −10 dB impedance bandwidth of 21.5% with a 3 dB AR bandwidth of 15.8% is acquired in a skin phantom. The antenna also exhibits good robustness to different thicknesses of biocompatible coating. The influence of different body phantoms is discussed to evaluate the sensitivity of the proposed antenna. The experiments are carried out in both skin-mimicking gel and pork, and the respective measured impedance bandwidths are 25.9% and 25.7%. The CP purity is experimentally validated by comparing the communication link levels in two orthogonal polarization directions. The maximum specific absorption rate (SAR) value satisfies the IEEE standard safety guidelines.

A Compact Broadband Antenna with Dual-Resonance for Implantable Devices.

A compact broadband implantable patch antenna is designed for the field of biotelemetry and experimentally demonstrated using the Medical Device Radiocommunications Service (MedRadio) band (401–406 MHz). The proposed antenna can obtain a broad impedance bandwidth by exciting dual-resonant frequencies, and has a compact structure using bent metal radiating strips and a short strategy. The total volume of the proposed antenna, including substrate and superstrate, is about 479 mm3 (23 × 16.4 × 1.27 mm3). The measured bandwidth is 52 MHz (382–434 MHz) at a return loss of −10 dB. The resonance, radiation and specific absorption rate (SAR) performance of the antenna are examined and characterized.

Design and simulation‐based performance evaluation of a miniaturised implantable antenna for biomedical applications

Biomedical telemetry is an emerging field of research which enables the formation of a transmission link from inside a living body to an external device. Implantable medical devices are now one of such valuable advancement in the field of biomedical telemetry. Implantable patch antennas are gaining attention and are becoming more of a choice for implantable medical devices that uses mostly RF telemetry. In this work, a state-of-the-art design for a rectangular implantable flexible patch antenna is proposed. The operation band for the antenna is chosen in the Industrial, Scientific and Medical (ISM) band (2.4-2.4835 GHz). The tiny dimension of the antenna, including the 9.45 μm thickness of the patch itself allows the antenna to be highly flexible and provides excellent results even at extreme bent conditions. For simulation environment, a three-layer human tissue model was used, where the antenna was encapsulated between the fat and skin layer. CST Microwave Studio was chosen to design and simulate the antenna. Several performance parameters were simulated, such as the operating resonant frequency, the return loss, radiation pattern, specific absorption rate and also sensitivity of the antenna when introduced to bending.

A Circularly Polarized Implantable Antenna for 2.4-GHz ISM Band Biomedical Applications

In this study, a single-fed broadband circularly polarized implantable patch antenna that operates at the 2.4-GHz Industrial, Scientific, and Medical band is designed for biomedical applications. The simulated impedance, axial ratio, and radiation patterns are studied in a cubic skin phantom. The influence of three other tissue models is also discussed. An impedance bandwidth of 6.2% with a 3-dB axial-ratio bandwidth of 8.13% is simulated in a one-layered-skin model. The experiments are carried out in both skin-mimicking gel and pork. The measured impedance bandwidths are 5.45% and 5.69%, respectively. Moreover, by setting the designed antenna in pork, an axial-ratio bandwidth as wide as 10% can be achieved. To the best of our knowledge, the proposed implantable patch antenna has the widest axial-ratio bandwidth at 2.4 GHz among all the reported ones.

Slotted Implantable Patch Antenna for ISM Band Application and Its Usage in WiMAX with an I-Shaped Defected Ground Structure

Slotted Implantable Patch Antenna for ISM Band Application and Its Usage in WiMAX with an I-Shaped Defected Ground Structure

Broadband circularly polarised implantable antenna for biomedical applications

A compact, broadband and single-fed circularly polarised implantable patch antenna is numerically evaluated and experimentally demonstrated for industrial, scientific, and medical band (2.45 GHz) biomedical telemetry application. By inserting a cross-shaped slot with unequal-length arms in the ground plane, the proposed antenna can obtain improvement for both impedance bandwidth and axial ratio (AR) bandwidth, without increasing the backward radiation. The simulated −10 dB impedance and 3 dB AR bandwidths are 16.15% and 6.09%. The measured impedance bandwidth is 14.03%. The overall antenna size (including the superstrate) is 10 × 10 × 1.27 mm3.

Dual-Resonant Implantable Circular Patch Antenna for Biotelemetry Communication

A compact broadband implantable circular patch antenna is designed and experimentally demonstrated for Medical Implant Communications Service (MICS) band (402–405 MHz). Compared with other similar implantable antennas, the proposed antenna incorporates three advantages for biotelemetry communication. First, it can realize a broad impedance bandwidth by exhibiting dual resonances. Second, it can obtain a compact structure by introducing two arc-shaped slots, a rectangular slot and a circular slot on metal radiating patch. Finally, it can display a friendly shape by using a circular structure. The proposed antenna occupies a volume of about 431.5 mm3(10.42× 1.27π mm3), which is a compromise between miniaturization and bandwidth. The measured −10 dB impedance bandwidth is 55 MHz (385–440 MHz). Furthermore, the radiation performance and human body safety consideration of the antenna are examined and characterized.

In Vivo Testing of Circularly Polarized Implantable Antennas in Rats

Two types of miniaturized circularly polarized (CP) implantable antennas are tested in a rat to investigate the effects of the live tissue on the antenna performance. The two implantable antennas are designed for Industrial, Scientific, and Medical (ISM) (2.4-2.48 GHz) biomedical applications. The first implantable helical antenna is initially designed in a one-layer muscle phantom for ingestible capsule endoscope systems. The second implantable patch antenna is designed in a one-layer skin phantom for wireless implantable devices with a fixed implant position. The footprint of the proposed antennas are π×(5.5) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ×3.81 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and 10 ×10 ×1.27 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , respectively. The two antennas were surgically implanted into the rat at Singapore Institute for Neurotechnology. The measured results in the rat were compared to the simulated ones in the one-layer phantom to evaluate the sensitivity of the antennas.

Capacitively Loaded Circularly Polarized Implantable Patch Antenna for ISM Band Biomedical Applications

A single-fed miniaturized circularly polarized microstrip patch antenna is designed and experimentally demonstrated for industrial-scientific-medical (2.4-2.48 GHz) biomedical applications. The proposed antenna is designed by utilizing the capacitive loading on the radiator. Compared with the initial topology of the proposed antenna, the so-called square patch antenna with a center-square slot, the proposed method has the advantage of good size reduction and good polarization purity. The footprint of the proposed antenna is 10×10×1.27 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The simulated impedance, axial ratio, and radiation pattern are studied and compared in two simulation models: cubic skin phantom and Gustav voxel human body. The effect of different body phantoms is discussed to evaluate the sensitivity of the proposed antenna. The effect of coaxial cable is also discussed. Two typical approaches to address the biocompatibility issue for practical applications are reported as well. The simulated and measured impedance bandwidths in cubic skin phantom are 7.7% and 10.2%, respectively. The performance of the communication link between the implanted CP antenna and the external antenna is also presented.